In a manufacturing process, priorities of lots to be released into a manufacturing apparatus are determined according to a predetermined rule. Examples of a priority determination rule using a remaining time until a scheduled shipping time (delivery time) and a scheduled remaining operation time until completion include (a) the lots are processed in order of increasing critical ratio (CR: a remaining time until the delivery time divided by a scheduled remaining operation time until completion) value and (b) the lots are processed in order of increasing slack (allowance) value (=time until the delivery time−scheduled remaining operation time until completion) (for example, refer to Japanese Patent Application Laid-Open Publication No. 2004-295679 (Patent Document 1)).